The present invention relates to a method of formulating a synthetic drug for use in animal feed, for the purpose of reducing carryover of the synthetic drug to subsequent lots of animal feed in the feed mill.
A growing concern has developed in the animal feed industry concerning the carryover of drugs in medicated animal feeds. Sulfamethazine, as an example of such a synthetic drug, exhibits electrostatic properties which cause it to cling to feed mill equipment so that when the equipment is emptied, and a different lot of animal feed is added to the mill equipment for processing, undesired sulfamethazine residues appear in that subsequent lot of animal feed. This also creates the problem of producing a uniform formulation, as well, if the subsequent lot of medicated animal feed is intended to contain sulfamethazine. A recent study has shown increased sulfamethazine residues in pork liver and kidney due to this drug carryover problem.
There is little prior art concerning the reduction of cross-contamination of feed mill equipment by medicated feeds. Chapman, in U.S. Pat. No. 4,211,781, teaches a process for preparing a substantially dustless animal feed premix by merely mixing the active ingredient with a non-toxic oil and an edible carrier.
Ludwig, in U.S. Pat. No. 4,048,268, teaches substantially the same process used in the present invention. The purpose of that invention was, however, related to a method of stabilizing the microorganism produced antibiotic tylosin, which is susceptible to deterioration causing a considerable loss of potency, but having no carryover problem.
The apparatus typically used in the process of the present invention is disclosed in U.S. Pat. No. RE27214, or U.S. Pat. No. 3,579,719. These patents teach the use of that apparatus for making spherical granules.
This invention greatly reduces the carryover of a synthetic drug in animal feed mill operations.